Combined type-writing and adding machine.



E. A. IIAIIT.

COMBINED TYPE WRITING AND ADDING MACHINE.

APPLICATION FILED` DEC. 9. |910. I

1,211,148. Patented Jan. 2,1917.

mr Non-nis uns Nom-umol. wAsumcmN, n. c.

F. A. HART..

COMBINED TYPE WRIIING AND ADDING MACHINE.

Arrucmon mm Dec. 9. |910- Patented Jal). 2, 19171 3 SHEETS-SHEET 2.

nu man "nu eo.. mutua. lnmwavou. 'It'.

F. A. HART.

COMBINED TYPE WRITING AND ADDING MACHINE.

M Pucnmu FILED No.9. 1910.

1,21 1,148. Patented Jan. 2, 1917.

3 SHEETS-SHEET 3.

m r .vmmls 51:12: ca.. mawumo.. vusnmamn. n, c.

UNITED sTATEs PATENT oEEIoE. A

FREDERICK A. HART, oF'HARTroR-n, CONNECTICUT, Ass'rGNoR, BY MEsNE ASSIGN-` MENTsTo UNnEiwvoonl COMPUTING MAoniNE COMPANY, or NEW YORK, N. Y., A

CORPORATIONy OF NEW YORK.

Specification of Letters Patent.

Patentedaan. 2, 1917.

Application filed December 9, 1910. Serial No. 596,451.

To all fur/tom t may concern: n

Be it known that I, FREDERICK A, HART, a citizen or' the United States, residing in Iflartford, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Combined Type-lVriting and Adding 'Machined of which the following is a specification.

The present invention relates to a mechanism primarily intended as a means-for operating, from a continuous source of power, one or more of the mechanisms of an adding nlachine, particularly such mechanisms as the adding mechanism, thecarriage-return mechanism, and other associated or intermittently operated mechanisms.

The invention has particular reference to typewriter adding machines, such for instance, that disclosed inthe patent to Hans Hanson, No. 816,319, dated March 27, 1906, and my application No. 466,836, filed December 10, 1908.

Reference is made for a more detailed understandingof the construction. and operation of the computing devices used in machines of this character, to Patent No. 1,190,171, dated July 4, 1916, which yis `a division of my application, No. 166,836, above referred to.

Certain .ofthe features of theinvention are however adapted for use in other adding n'iachines, and in machines in which the source of power is not continuous.

It is desirable, as a matter of convenience, to save time and labor, that the mechanisms above enumerated, forming part of the adding machine, be operated` from a source of power and that this source of power be more or less independent. of the adding machine, when continuous. Heretofore typewriter adding machines ofthe Hanson type have not been so constructed. Since the time or period during which the source of power is erlectve may be different from the period during which it is needed, said source must be normally ineffective to operate the adding mechanism and the carriage-return mechanism, as, for example, when the source of power is continuous, and therey must be a suitable .key control for effectively clutching these mechanisms to the motor driven train when the same are to be operated; and there must be suitable means for unclutching the driving train from these mechanisms' as soon as their functions are performed. In order thatthe unclutching operation may be proporly timed, and in order to avoid the neces-l sity of a double operation of the control key, the unclutching operation should be automatic. The clutch should be positive to insure proper movement and Operation of the mechanisms controlled thereby, and yet provision should be inade to permit of yield in the drive to accommodate the mechanisms to sudden loads, and to permit the drive to slip continuously when by any accident the machine is blocked.

It is an object of the present invention to provide an eliicient power drive, particularly adapted to typewriter adding machines.

1t is an object to provide a key control whereby the adding mechanism and the carriage return mechanism may be promptly and positively connected to a source of power which may be adapted to run continuously. Vi

t is an object to provide a means for automatically disconnecting the adding mechanism and the carriage return mechanism from the source of power so soon as each cycle of action of these mechanisms is completed. v

A further feature of the invention is to provide a means, which, while still permitting of the positive connection of the adding mechanism to' the source of power, nevertheless permits of slip in the driving connections in event of overload or blocking of the machine.-

A further feature of the invention is to provide 4afmeans for rendering inoperative the connecting means to the source of power, so that on especial occasions, such as during the'correction of an error, the power drive cannot be connected to operate the adding and carriage return mechanisms.

More specifically, the form of the invention herein disclosed embraces: a form of positively acting clutch and key controlled trip mechanism for operating the clutch; also an arrangement and construction of the driving gearing whereby the rotary drive of the motor is transformed into a reciprocating drive for the adding incohanism; also a form of friction clutch and means for adjusting the friction thereof to the normal and proper load of the adding mechanism so that there will be no slip except in event of overload ory blocking of the machine; also a means for locking the clutch against operation when desired; also an arrangement and mounting of the driving mechanism such that without the disassembling of the same and without disconnection thereof from the motor, the same may be nevertheless disconnected, readily and by a single operation, from the adding mechanism to permit of removal of the adding machine or adjustment of the parts thereof.

Other objects and features of the invention will hereinafter appear.

In the accompanying drawings, Figure 1 is a view in side elevation, partly cross sectional and broken away, showing a typewriter adding machine and the motor driven mechanism of the present invention for operating such machine. Fig. 2 is a view in front elevation, partly cross sectional, showing the motor driven mechanism connected to the adding and associated mechanisms, and showing the key operated control mechanism. Fig. 3 is a view in cross sectional elevation of the friction clutch which connects the motor to the driving train. Fig. i is an end view of the clutch shown in Fig. 3. Fig. is a view in cross section on the line of Fig. 2. F ig. 6 is a view in end elevation of the motor and driving mechanism; the typewriter frame being broken away to show parts of the mechanism within the same. Fig. 7 is a detail view in top plan showing the key controlled trip lever for operating the trip pin; and the mounting of the same on the frame.

In Fig. 1 the base plate 1 of the typewriter is shown supported upon standards 2. The motor and mechanism which forms the present invention is attached tothe frame work below the base plate l. rlhe motor 3 is indicated as an electric motor having a suitable drive shaft 4t. It will be understood, however, that the motor may be of any desired character and instead of being mounted directly on the drive shaft a below the base plate, may be situated at any suitable point and connected by gearing to the drive shaft. The drive shaft -i rotates continually but its action is transmitted to the typewriter adding and carriage return mechanisms only when it is desired to actuate such mechanisms and when for this purpose a suitable key 5 is depressed. The adding and carriage return mechanisms will not be described in detail although the same are shown in part in the various drawings, because these mechanisms are fully set forth and described in the patent to Hans Hanson, No. 816,319, dated March 2T, 1906, and my application iiled December 19, 1903, No. 466,836. The motor shaft 4, being directly connected to the motor, would, if also positively connected to the adding mechanism. be nonyielding in its action on the adding and carriage return mechanisms. In order that the connections from the motor to these mechanisms may yield slightly at sudden loads, or may slip continuously if blocked by accident to the machine, there is interposed between the motor and these mechanisms a friction clutch, the friction of which may be adjusted so as to carry, without slip, the full load required for the proper operation of the mechanisn'is, but so as to permit of slip in event of excess load. The mechanisms are therefore driven, not directly from the shaft l, but from a shaft 6 (see Fig. l) alined with the shaft -1 and connected thereto by the friction clutch. Keyed to the end of the shaft if (see Fig. 3) is a sleeve 7 having integral therewith on its end a disk 8 which forms one member of the friction clutch between the shafts Ll and 6. Loosely mounted on the sleeve T, to have longitudinal movement thereon, is a disk 9 which forms the member actually driving shaft 6. Between the disks S and 9 is a dis-k 10 of suitable friction material. The disk 9 is connected to the shaft 6 to rotate therewith by means of an arm 11 fast to the shaft 6 and having an off-set portion or tooth 12 which extends over the disks 8 and 10 and lies between two ears 13 (see Figs. 3 and L1) on the disk 9. A coiled compression spring lt bears at one end against the disk 9 and at the other end against a nut 15 fast to the sleeve 7. The tension of the spring let is so adjusted by means of the nut 15, that under the normal load the disk 9 is forced against the disk 10 and the latter against the disk 8 in such manner that the shaft i with the disk 8, in revolving, carries the disk 9 and through the medium of the arm 11, also carries the shaft 6. It will be noted, however, that when the load on the shaft 6 exceeds the predetermined capacity of the spring there will bc slipping between the disks 3 and 9, so that the shaft a may nevertheless revolve without injury to the machine.

The adding and the carriage-return mechanisms to be driven from the shaft 6 are actuated by means of a longitudinal reciprocated rack 16 just above the base plate 1 and forming part of a general operator or actuator for running up digits accumulated by the computing' mechanism. This rack and the mechanisms operated thereby are fully described in the Hanson patent above referred to. For actuating the rack from the motor, there is adjustably attached to the rack a. yoke 17 engaging the upper end of an arm 18 mounted on a cross head 19 as more particularly shown in Fig. 5. rihe cross head 19 is carried on a slide 20 which has bearing and reciprocates within extensions 21 of a casing 22. The reciprocation of the slide 20 with the cross head 19 is transmitted by the arm 1S and yoke 17 to the rack 16 so that the slide 2O and the rack 16 move together at all times. The casing 29. and the base plate 1 are slotted at Q3 and 241 respectively to permit of engagement of the arm 18 with the yoke on the rack. The slide 20 is shown as a cylindrical bar having an elongated` oil groove 27. The yoke 17 is adjustable on therack 16 so that the parts may be set to give the proper movement to the rack. The slide Q() with the cross head 19y is reciprocated by means of a crank Z5 ona shaft. which latter has rotary movement in a bearing sleeve 27 integral with the casing 22 containing the cross head 19. The crank 25 is connected to the cross head by means of a block 28 pivotally attached to the crank, and mounted to have up and down reciprocatory movement in a guide way i0 in the cross head 19. By means of the block 28, the rotary movement of the crank is transformed into a reciprocating movement of the cross head. A half revolution of the crank 25 from the position shown in Fig. 5 causes the cross head'and slide 2O to be shifted with the rack 16 a full stroke to the left; the crank, continuing its revolution, then carries the slide and the cross head back to normal position shown in Fig. 5. For every complete revolution of the shaft 26, there is therefore a complete forward and return movement of the cross head with the rack. Integral with the bearing sleeve 27a and at the right hand end thereof is a second casing 30 into which the shaft 26 protrudes. The casing 30 has a cylindrical sleevelilre portion 31 in which the shaft 6, (heretofore described as` connected by the friction clutch to the power shaft 4), is mounted to have rotary movement in suitable bearings (see Fig. 1). The shaft 6, it will be recalled, may rotate continuously, (except when operatively connected to the adding mechanism, under such conditions of overload of the latter as to cause slipping at the friction clutch), whereas the shaft 26, which is positively connected to the operating rack 16, must only rotate when the adding mechanism is operated. Consequently, between the shaft 26 and the shaft 6 which drives the same, there must be a suitable clutch mechanism for connecting the shafts when the adding mechanism is to be operated and for disconnecting the shafts at other times. The construction of this clutch and the means for operating the same is as follows: Mounted to revolve loosely on the shaft 26 is a worm gear The worm gear 32 gears lwith a worm 33 on the shaft 6, and consequently rotates continuously with shafts 6 and 4. Fast to the shaft 26 is the cup member 34 of the control clutch. Fast to the hub of the gear 3Q in a hardened bearing ring or collar 35, between which and the inside face ofthe clutch cup is a grip roll or ball 36, which when gripping both the clutch cup and the collar 35 transmits the movement of the latter to the cup, and hence to the shaft nhe roll 36 projects wit-hin a pocket 37 in the inside face of the clutch cup. This pocket is cam shaped, so that in one position the ball or roll 36 may grip both the bearing ring and the clutch cup to Lcanse the two to rotate together, whereas in another position of the roll in its pocket, the grip of the roll on the collar is released to permit the latter to rotate idly and independently of the clutch enp 31 and shaft QG.

The gripping ball or roll is shifted between gripping and releasing positions in the pocket 37 by means of an annular member or ring 38 which rides loosely on the collar within the cup 31, and which is cut away at one point 'to receive the roll 36, so as to engage the roll on both sides thereof, as shown in F ig. 1. Rotation of the ring 38 on the bearing collar 35 therefore results in a shift of the gripping roll or ball. Vithin a pocket 39 in the ring 38 is a coiled Acompression spring 40 bearing at one end against the ring 38 and at the other end against a stop -11 secured to the inside of the clutch cup. The pocket 39 is of sufficient length to permit of the movement of the ring 38 without interference by the stop 41. The pressure ofthe spring -10 tends to turn the ring 38 with the roll 36 in such a direction as to cause the clutch cup and n the bearing collar to be locked together by the gripping' roll. Unless otherwise prevented, the spring et() would therefore always act to .lock the shafts 26 and 6 to cause the same to rotate together.' Since, however, such locking of the two shafts is only desired when the adding mechanism is to be operated, the ring 38 must normally be held against the action of the spring 40, with the roll 36 in such position as to prevent gripping by the roll.

For holding the ring 38 in releasing position, there isa stop or trip pin 13, carried by the casing 30, and adapted to be moved into and out of engagement with a tooth y or detent L14, which latter is integral with the ring 38 and proj ects through an opening in the horizontal flange of the clutch cup. rfhe stop pin 43 is movable into and out of reach of the tooth 44 by mechanism operated from the ley 5. When in the position shown in Fig. 1, the stop pin 13 engages the tooth 41,

and thus holds the ring 38 against the action of the spring 40; so that, at this time, the gripping roll is held in position where it is inefective to grip the clutch cup to the worm gear. This is the normal position of the parts. hen the shaft Q6 is to be locked to the shaft 6, the pin is lifted so as to disengage the pin from the tooth 4i. The spring 40 is then free to throw the ring 38 with the roll 36, thus locking the clutch cup to the worm gear, and causing the rotary movement of the shaft 6 to be picked up by the shaft 26. lhen the clutch cup is rotated, the ring 38 with its tooth 44 is also rotated, so that the tooth 44 moves past and away from the pin 43. If after the tooth 44 passes the pin 43, the pin 43 is promptly dropped back to normal position, it will be struck by the tooth 44 as the latter completes its rotation, and will thus cause the ring 3S to be forced back against the action of the spring 40 to release the clutch cup from the worm gear. For each operation of the adding mechanism, the stop pin 43 is lifted, and then promptly dropped, thus causing the parts to make one rotation together, and thereupon to be disconnected by pin 43 when the tooth 44 strikes it on completing the revolution.

The key 5 which operates the trip or stop pin 43 is carried on a key stem or plunger 45 having pivoted at its lower end a lever 46, in turn pivoted to the frame of the machine at 46a. A lever 47 which directly engages the trip pin 43 is pivoted to the frame at 48 and crosses under the lever 46 in such manner as to be engaged and rocked by the latter when the key 5 is depressed. The lever 47 at one end engages between two shoulders 49 and 50 on the head of the trip or stop pin 43, and at the other end carries an adjustable yoke 51 upon the top of which the key lever 46 bears when the key is depressed. The yoke 51 is adjustable around a pivot 52 on the lever 47 by means of set screws and thus provides for accurate setting of the connections so that the position and movement of the trip pin by the lever 46 may be fixed with accuracy. The fulcrum 4S of the lever 47 is also adjustable to predetermine the proper position and movements of the parts, and to this end it is mounted upon a block 54 adjustable, b v means of set screws 55, on the frame of the machine. Depression of the key 5 therefore causes the lever 46 to be depressed, andthe latter pressing upon the lever 47 rocks the same in such manner that the trip pin is lifted and thus disengaged from the detent or tooth 44 in the clutch device. The key 5 with the lever 46 is returned to normal position by a spring 56 (see Fig. 6). The movement of the key lever in both directions is determined by a stop pin or bar 57 which lies within a slot 5S in the key stem, and which by engagement with the end walls of the slot determines the movement of the key and connected parts. A leaf spring 67 attached to the frame of the machine, bears against the head of the trip pin 43 and returns the same with the lever 47 to normal position when the key 5 is released.

In order that the key 5 may not be operated to apply the power while the error key 68 is depressed, there is operated from the error key a hook 69 which is adapted to be moved on its pivot 70 under a hook 71 on the trip lever 47, thus holding the trip lever against operation by the key lever 46. The error key stem 72 on depression rocks a bell crank lever 73, one arm of which is connected to a slide bar or link 74. Attached at one end to the link 74, and at the other end to the hook 69, is a spring 75 tending to pull the hook 69 into engagement with the hook 71, but normally prevented from so doing by means of a rod 76 which engages at one end the face of the hook 69 and at the other end bears against a stop 77 on the slide bar 74, to which stop one end of the spring 75 is attached. Spring 75 is a coil spring, embracing and supporting the rod 76. Vhen the error key 68 is depressed, the slide 74 moves forward with the stop 77, and the spring 75 is then free to move the hook 69 under the hook 71.

l/Vhen the error key 68 of the Hanson typewriter adding machine is depressed, ceru tain parts are elevated to unset the pins which have been set by the number keys. The parts so elevated are moved into the path of the adding mechanism; and, it at this time, the key 5 could be depressed to connect the motor, the resetting parts would be struck by the adding mechanism. To prevent this, the trip lever 46 is locked by the error key in the manner described.

The motor driven parts may be disconnected from the adding mechanism, and the arm 18 disengaged from the rack 16 by swinging the casings 22 and 30, and this connecting sleeve 27 together with all parts contained within said casings, around the axis of the shaft 6 as a pivot. To this end, the sleevelike portion 31 of the casing 30 is mounted to turn in trunnions formed by rings 58L and 59, carried by the bracket 60 which supports the casing from the base plate. The casing 22 rests upon a cam lever 6l pivoted at 62 to a bracket 63, also attached to the base plate. lVhen the cam lever 61 is turned down 90 degrees from the position shown in F ig. 2, the casings 22 and 30 turn in the trunnions 59l and 59 sutilciently to withdraw the arm 18 from the rack 16. The casing 22 then rests on the other face of the cam lever, and the typewriter may be removed or the parts thereof adjusted and the adding operation performed by hand (as described below) without reference to the motor connections. Re verse movement of the cam lever brings the parts again to Fig. 2 position. The movement of the parts in the trunnions 58a and 59 is guided by a lug 64 on the end 65, of the casing 22, which moves in a milled slot or groove in the bracket 63. The lug 64 on the casing 22, by engagement with the bracket 63, also acts to take the thrust of the reciprocating parts Within the casing when the adding mechanism is being oper ated.

The return of the carriage is effected from the rack 16 through the medium of a pinion 80 on a stud shaft 81 meshing with the rack 16 and with a segmental rack 82 fast on a shaft 83. Loose on shaft 83 is a gear 84 which meshes With a pinion 85 which is fast on a shaft 86 with a drum 87. Attached at one end to the drum 87 is a draw band 88 Which is led over an idler 89 ony a bracket 89 under a guard 90, and is attached at its other end to the carriage return and line spacinglever (not shown) of the typewriter. During the feed of the carriage, the band 88 is paid off of the drum 87, but when the rack 16 is moved forward in the manner hereinbefore described, the drum 87 is revolved so as to Wrap upon it the band 88, thereby drawing upon the carriage return and line spacing lever to return the carriage and to line space the platen.

The adding mechanism comprises a reciprocating frame supported, at one side of the machine, on the rack 16, and at the other Side of the machine on a bar 91. This frame comprises two bracket arms 92 attached to rack 16 and to bar 91 respectively; and also tivobars 93 and 94, disposed longitudinally of the machine and attached at each end to one of the bracket arms 92. As set forth in the Hanson patent referred to, the bar 93 is the setting pin-lever bar, Which, When moved forward with the rack 16, engages and moves the pin levers (not shown) to effect the adding operation. The other bar 94 upon return of the rack 16 engages the pin-levers to return the same to normal po sition. In the I'Iart adding machine, the adding and carriage return mechanisms are operated, in a manner fully disclosed in the aforesaid Hart application by means of lever 95 fast on shaft` 83 and so rotated by segment 82 coperating with lever 96 loose on the shaft 83, said levers 96 and 95 carrying pinions 97 and 98 meshing With gear 84. Then rack 16 is reciprocated, it turns the segment 82, rotating shaft 83 and so pinion 98 rides forward idly on gear 84 till it meshes with pinion 97, when, owing to the fact that the pinions attempt to rotate against each other, they lock to the gear 84 to effect the rotation of the latter, and thus rotate drum 87 through the agency of pinion 85, thereby drawing the carriage back by means of band 88. On the reverse stroke of rack 16, segment 82 swings arm 95 backivard and pinion 98 frees itself from pinion 97, and so segment 82 brings pinion 98 back to its initial point. The letter-feeding motion of the carriage rotates drum 87 by un- Winding band 88 therefrom, and so through pinion 85 it rotates gear 84 Which carries pinion 97 With it till both come to rest Where they stood at first With the carriage at the limit of its travel. A concealed spring in drum 87 keeps the band 88 taut, so that it will not tangle with the mechanism if the carriage is returned by hand. The poner-driving connections of the present invention do not prevent a hand operation of the machine if it is desired to so operate the machine, and the levers 95 and 96 are therefore shown.

In F ig. 1, the carriage 99 is shown mounted on the frame 100 of the typewriter. Carriage release key 101 and paper release key 102 are shown on the carriage. The platen is indicated at 104, and at 105 is shown the arm of the platen shift frame. Mounted on brackets 106 at the rear of the machine is the rack 107 on which are set the selector lever stops 108 of the Hart adding machine. The selector stop levers 109 are pivoted at 110 to a bracket supported on arms 111, and are connected to the pin levers by Wires not shown, but which lie Within the member 112. The structure, and the manner of setting the pin levers from the stop levers are set forth in detail in the aforesaid Hart copending application.

In operation, assuming the parts to be in the position shown in Figs. 1 and 2, the figures to be added having been Written, so that it is desired to operate the mechanism which does the adding and also to operate members 34 and 35 are therefore disconnected. Key 5 is now depressed and with it the stem 45 and lever 46. Lever 46 rocks lever 47 in such manner as to lift trip pin 43. Spring 40 immediately throws the ring 38 and grip ball 36 to lock yclutch cup 34 to collar 35. Rotary movement is then transmitted from Worm gear 32 to shaft 26 and crank 25. Crank 25 reciprocates the cross head 19, slide 20, arm 18, and rack 16. Rack 16 operates the adding mechanism in a manner explained in the Hanson application heretofore referred to. One reciprocation of the rack 16 effects the adding'operation and also returns the carriage. In the meantime the grip roll 36 is carrying the ring 38 with Vgear 32 and Worm 33 may be designed'for any desired reduction of revolution between the motor and the shaft 26, or intermediate gearing may be inserted. A hand wheel 66 is shown on the shaft 4 whereby the driving mechanism may be actuated by hand when desired.

There has been shown and described an eiicient form of motor driven mechanism and key control for operating the adding mechanism and the carriage return mechanism of a typewriter adding machine. It is obvious however that other and various forms of motor driven mechanisms for this purpose may be devised within the scope of the invention. It is also obvious that the key operated control mechanism, and the clutch mechanisms are also subject to variation without departing from the scope of the invention.

Variations may be resorted to within the scope of the invention, and portions of the improvements may be used without others.

Having thus described my invention, I claim:

l. A mechanism for operating the adding mechanism of a typewriting machine from a source oi power, comprising a motor, an actuator for the adding mechanism. means for connecting` the motor to the actuator to effect the movement of the latter, an error corrccting mechanism, and means for rendering inoperable the connection from the source of power to said actuator during the operation of the error correcting mechanism.

2. A mechanism for operating the adding mechanism of a typewriting machine from a source of power, comprising a. motor, an actuator for the adding mechanism, means for connecting the motor to the actuator to effect the movement of the latter, an error correcting mechanism, a key for operating said error correcting mechanism, and means controlled by said key for rendering inoperative the connection from the source of power to said actuator during the operation of the error correctingmechanism.

3. ln a computing machine, the combination, with computing mechanism, and a driving mechanism therefor; of a key; an arm controlling said driving mechanism, and cont-rolled by said key; a second key; and an arm movable by the second key for locking the iirst-named arm against operation by the first-named key during the time that said second key is depressed.

at. A computing machine comprising key, an arm moved b v said key, a stop, a spring moving said stop to lock said arm, a second arm, a stop on said second arm holding said spring-moved stop inoperative, and a key moving said second arm to cause said first arm to be locked.

5. A computing machine comprising a key, an arm moved by said key, a driving mechanism controlled by said arm, a stop, a spring` for moving said stop to lock said arm, a second arm on which said spring is anchored, a. stop on said second arm holding` said spring-moved stop inoperative.l and av key to operate said second arm to lock said first arm.

G. In a computing machine, the comliination of an error-correcting mechanism; a computing mechanism drive; and means for rendering said computing mechanism drive inoperative while said error-correcting mechanism is being operated.

7. The combination with a typewriting machine and an adding mechanism connected thereto, of a motor and actuator for the adding mechanism, means for connecting the motor to the actuator to effect the movement of the latter, an error-correcting mechanism, a key for operating said error-correcting mechanism, and means controlled by said key t'or rendering inoperable the connections from the motor to the actuator during the operation of the error-correcting mechanism.

8. In a computing machine, the combination'with manual and power driving devices, of an error key. and means etlective on the power device only for preventing op e 'ation of the same while the error key is in operation.

9. A computing machine comprising a key; an arm moved thereby and provided with a lug; a` swinging hook arranged to engage said lug to prevent movement ot' said arm; a spring normally tending to swing depressible arm; an operating key therefor;

a swinging member arranged to catch under said arm to lock the same against depression; a` spring normally tending to swing said member to locking position; and

a key-actuated member normally preventing action of said spring but when moved, permitting action thereof for controlling said catch member.

1l. In a computing machine, the combination. with computing mechanism, and a general operator therefor; of a motor connected to drive said general operator; a key for controlling the drive; an error key; and means operated by said error key, when the latter is depressed, for locking said controlling key against operation.

FREDERICK A. HART.

lVitnesses z K. FRANKFORT, C. RIPLEY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patenti, Washington, ID. C. 

